<!doctype html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>
	<script src="jquery-2.1.1.min.js"></script>
</head>
<body>
	<p>A</p>
	<select name="test" id="test">
		<option value="12">1</option>
		<option value="2">2</option>
		<option value="3">3</option>
	</select>
	<script>
		$("#test").val(3);
	</script>
</body>
</html>